Adequate blood supply and the storage thereof is a problem facing every major hospital and health organization around the world. Often, the amount of blood supply in storage is considerably smaller than the need therefor. This is especially true during crisis periods such as natural catastrophes, war and the like, when the blood supply is often perilously close to running out. It is at critical times such as these that the cry for more donations of fresh blood is often heard. However, unfortunately, even when there is no crisis period, the blood supply and that kept in storage must be constantly monitored and replenished, because stored blood does not maintain its viability for long.
Stored blood undergoes steady deterioration which is, in part, caused by hemoglobin oxidation and degradation and adenosine triphosphate (ATP) depletion. Oxygen causes hemoglobin carried by the red blood cells (RBCs) to convert to met-Hb, the breakdown of which produces toxic products such as hemichrome, hemin and free Fe.sup.3+. Together with the oxygen, these products catalyze the formation of hydroxyl radicals (OH.cndot.), and both the OH.cndot. and the met-Hb breakdown products damage the red blood cell lipid membrane, the membrane skeleton, and the cell contents. As such, stored blood is considered unusable after 6 weeks, as determined by the relative inability of the red blood cells to survive in the circulation of the transfusion recipient.
Many patents have addressed different aspects of blood storage. One such patent is U.S. Pat. No. 4,837,047 to Sato et al. which relates to a container for storing blood for a long period of time to keep the quality of the blood in good condition. The patent is directed at improving the storage life of the stored blood by maintaining a partial pressure of carbon dioxide gas in the blood at a low level. Such partial pressure is apparently obtained through normalization with the outside atmosphere. The container is made of a synthetic resin film which has a high permeability to carbon dioxide gas for the purpose of making it possible for the carbon dioxide gas to easily diffuse from the blood to outside. However, the problems caused by the interaction of the oxygen and hemoglobin in the blood are not addressed.
Another patent, U.S. Pat. No. 5,529,821 to Ishikawa et al. relates to a container and a method for the storage of blood to prevent adhesion of the blood to the container. Blood is stored in containers composed of a sheet material having a plurality of layers where a first sheet which contacts the blood substantially prevents the activation and adhesion of blood platelets to the layer. Again, however, the problems caused by the interaction of the oxygen and hemoglobin in the blood are not addressed.
There is, therefore, a need to be able to store blood on a long-term basis without the stored blood undergoing the harmful effects caused by the oxygen and hemoglobin interaction. Furthermore, the blood storage devices and methods must be simple, inexpensive and capable of long-term storage of the blood supply.